And polishing school-slates



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HENRY W. HARPER, OF BERLINSVILLE, PENNSYLVANIA.

Letters Patent No. 95,341, dated September 2S, 18679;v antedated'Ma/rch. 29, 1869.

IMPROVE!) MACHINE Il-"OR` G-RINDING- AND POLISHIN G- SCHOOL-SLA'ES.

The Schedule referred to in these Letters Patent and making part of the same.

To all whom it Imay concern:

Be it known that I, HENRY W. HARPER, of Berlinsville, Northampton county, Pennsylvania, have invented an Improved Machine for Grinding and Polishing School-Slates; and I do hereby declare the following vto be a full, clear, and exact description of the same,

reference being had to the accompanying drawing, and to the letters of reference marked thereon.-

My invention consists of certain mechanism, fully described hereafter, for grinding and polishing'crude slates, and rendering them available as school-slates.

In order to enable others skiiled in the art to make and use my invention, Iwill now proceed to describe its construction and operation, reference being had to the accompanying drawing, which forms a part of this specification, and in which- Figure 1 is a vertical section, on the line 1-2, iig. 3, I

of my improved slate-grinding and polishing machine;

Figure2 is avertical section on the line 3-4, fig. 3;

Figure`3 is a plan view, partly in section; and

Figures 4 and 5, detached views, illustrating my in-' vention.

Similar letters refer to similar parts throughout'the several views.

A is the frame of the machine, in suitable bearings on which, turn the vertical shafts B, C, D', E, and F, andthe horizontal shaft G, each shaft being provided with a suitable driviugpulley. y l A A horizontal driving-disk, H, secured to the vertical shaft B, restsupon a collar, a, and is contained within'.

an annular metallic band, b, which is secured to the four cross-pieces c of the frame A.

4Four rods, d, (see g. 4,) passing through openings in the band l1, meet at a centralhub, e, through which the shaft B passes freely. l

Above the disk H, andupon the Shad B, is a sleeve, I, to the lower end of which is secured a grinding-disk, J ,which turns partly withinthe band b, above described, and which has fonrfor more slits, f.

This disk may be raised or lowered, atpleasure, by means of a Weighted lever, g, which is hung to the frame A, and whose forked short arm enters an annular groove, 71., formed in the sleeve I.

The shaft B is furnished with a band-pulley, j, and the sleeve I with a pulley, k, so that the two grindingdisks H and J may be revolved in opposite directions.

The vertical shaft C, as well as the shaft E, may be raised or lowered by a weighted lever, m, or other suitable appliances.

0n the upper end of the shaft O is a horizontal wheel, on the edge of which is a band, n, projecting above the face of the wheel, as shown in iig. 2.

A split ring, p, which rests in the circular recess qV of the wheel, also projects above the face of the same,

and is connected to thc'band n ,by bolts r, which passv l' throiigh the wheel.

By turning the nuts s upon the ends of these bolts r, the diameter of the split ring p may be increased or diminished at pleasure. y

Upon the upper end of the shaft D, and overlapping the wheel K, is a grinding-disk., L.

To the' upper end ofthe shaftE is secured a wheel, M, precisely similar to the wheel K before described, this wheel M being overlapped'by the grinding-disk L,

on the shaft D, as well as by a similar disk, P, on thev Upon the horizontal shaft G is secured a polishingwheel, R, and to a sleeve, S, turning upon the said shaft, is secured a similar polishing-Wheel, T.

Passing between these wheels, and'above the shaft G, is a rod, U, secured to standards c, and tightened by a nut, w. (See figs. 1 and 3.) Y

By means of'a levercshown in red lines, iig. 3, the wheel T is kept close up to the rod U.

The rough slab to be converted into school-slates is split or sawed to a proper thickness, and then cut tothe size desired. These rough slates, which are similar to those used for roofing, are placed upon the ,grindingdisk H, between i disk J being 'first raised by means of the lcverg. Upon releasing the lever, the disk J is lowered until it rests upon the slates, when the two disks are caused to re-` volve in opposite directions, as shown by the arrows,

fig. 3. The slates are prevented from being carried round with either of the stones by the bars d, and the grinding is facilitated by the use of sand, which is introduced to the slates through the slits f of the upper disk, and the pressure upon the slates is regulated by the weight upon the long arm ofthe lever g. Between the disks Hand J, the slates are reduced to a uniform thickness, and all prominent inequalities removed. Thence they are removed to the wheel K, and placed radially between the rings In and .11, as shown in hg; 3. When'the required number of slates has been Iplaced on the wheel, the nuts s are tightened,thereby increasing the diamcterof the :split ring p, and forcing the slates against the band n, between which and the ring they are securely confined. l

The shafts (l and D are now rapidly rotated in opposite directions, and the wheel K is elevated toward the grinding-disk L, until the slates are in contact with and are acted o'n bythe said grinding-wheel. When properly reduded, the lslates are turned, so thattheir opposite faces may be acted on.

From the wheel K, `the slates are removed to the wheel M, and confined to the same, so as to be acted on by what may be termed the rst polishing-wheel P, the full weight of which on the slates is not necessary;

the bars d,`as shown in iig-4, the

hence the shaft F of this polishing-wheel rests on the spring t.

The slates are taken from theA wheel M, and submitted to the final or polishing-process, which is as follows:

A high rate of speed is imparted to the polishingwheels R and .Td which turn in opposite directions, as shown in fig. 3, and the slates to be polished are placed, edge downward, on the rod U, and passed between the wheels, dry slate-powder, or an equivalent substance, being used in the operation. The wheel .l is pushed up to the slates by its lever shown in red lines, iig. 3.

It will be observed, that the wheel K always revolves e inthe same plane, that the grinding-disk L can beraised and lowered, whereas the polishing-disk P revolves in the same plane, while the wheel M admits of being raised or lowered-an arrangement which prevents the grinding-disk L ifrom coming in contact withl the slates confined on the wheel M for being acted on by the polishing-disk I.

In many cases, the slates are of so perfect a character, that the preliminary grinding by the disks J and H- may be dispensed with, the slates being at once placed on the wheel K, tombe acted on by the grindingdisk L. The final polishing-process, by the wheels R and T, may also be dispensed with, if the Vpolishing-v disk P be sueiently ne.

Both the grinding-disk Land polishing-disk P have surfaces of emeryror consist of the well-'known emerywheels now in general use for grinding and polishing; in faot,1 have found emery to be a material especially applicable to the reductionand polishing of slates.

dotted lines, iigs. 2 and 3, may bensed to act on the slates in the wheel K.

1I do not desire to confine myself to any particular volving in contrary directions, inl combination with the bars d, or their equivalents.

2. The disk H, and its band, d, in combination with the movable disk J, and its slots, f.

3. rlhe revolving wheel K or M,4 constructed substantially as'described, for holding the slates, in cornbiuation with a grinding or` polishing-wheel or disk.

5. The combination of a revolving wheel, K or M, for holding the slates, with one or more horizontal relap the said wheel, as set forth. p

6. The combination of the two vertical polishingwheels T and R with -the bar V, for the purpose specified.

In testimony whereof', I have signed my name to this specification, in the presence of two subscribing witnesses.

H. NVM. HARPER.

Witnesses:

H. HowsoN, NV. J. R. DELANY.

If desirable, a .second grinding-disk, L', shown by j arrangement of frame-work, or to the precise construction or arrangement of the several parts herein de- I claim as my invention, and desire to secure by Let- 1. The two horizontal grinding-disks J and H, re

4. The wheel K, its band, the split ling p, and bon'r.

volving polishing or grinding-disks, :arranged to over-` 

